Protective circuit breakers are known, for example, in the form of low-voltage circuit breakers. Protective circuit breakers of this kind have a switch housing in which a switching contact for at least one voltage phase is arranged, the contact elements of the switching contact resting against one another when the switching contact is closed and being separated from one another when the switching contact is open. In this case, one contact element is designed such that it can move.
The two contact elements of the switching contact are each electrically connected to a connection piece, which connection pieces extend on the rear side of the switch through the switch housing to the outside. The connection pieces are each connected to a main busbar.
In order to fulfill the protective function, converters are provided which are arranged in a converter housing which has a passage opening through which one of the two connection pieces runs. At least one converter coil is arranged in the converter housing around the passage opening and therefore around a connection piece and is connected to an electronics system. The electronics system processes the converter signals and opens the switching contact, for example in the event of a short circuit. The converter housing is expediently located in a recess in the switch housing. The converter housing is covered to the outside by a plate-like converter cover. The converter cover likewise has a passage opening through which the connection piece which extends through the converter housing runs.
It is often desirable for the protective circuit breaker to be equipped with a voltage measuring system which taps off the voltage from the connection pieces and therefore from the main busbars and detects the voltage profile with respect to time. The voltage tap has to meet relatively strict requirements in respect of insulation and mechanical strength in order to be able to withstand the electrical and mechanical loads.